This invention relates to wheelchair propulsion means and has particular application to the construction of wheelchairs or to the provision of a sub-frame containing the propulsion means so that it can be fitted to existing wheelchairs.
In the past, wheelchairs have had three main forms of propulsion. These are: Pushing from behind by a nurse or other assistant; Direct operation on the large diameter main wheels; and Electric drive.
The first involves the use of another person, and is impossible when the user is alone and left to fend for himself. The second requires the user to grip the top of the wheel, or the top part of a secondary rim attached around the outside of the wheel, by pulling and pushing it forward. This can require quite a considerable amount of exertion by the arm muscles in a direction and position that is not ergonomically efficient. The third is expensive, renders the wheelchair somewhat heavy, and sometimes leads to difficulties in terms of manoeuverability.